Antimicrobial acrylic polymer

ABSTRACT

An antimicrobial additive composition is provided which economically and efficiently imparts antimicrobial characteristics to acrylic polymers, and particularly thermoformable acrylic sheets made from such polymers. The antimicrobial composition comprises an alkyl dimethyl ammonium saccharinate, an oxathiazine, an azole, an isothiazoline, a chlorothalonil, and/or mixtures thereof, among others.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. provisionalapplication No. 60/498,491 filed on Aug. 28, 2003, and from U.S.provisional application No. 60/536,875 filed on Jan. 16, 2004, each ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to polymer materials, inparticular to polymers which are resistant to the growth of certainmicrobiological species such as bacteria and fungi. In particular, thepresent invention relates to sheets of acrylic polymers that arethermoformable.

The acrylics group of polymers is dominated by two resins—one usedprincipally for blending with other resins and as a fiber(polyacrylonitrile or PAN) and the other used principally for molding(polymethylmethacrylate or PMMA). The present invention is directedprimarily toward PMMA.

The molding resin, PMMA, is a very popular engineering thermoplasticmaterial. Common brand names for PMMA include Perspex®, Plexiglas®,Lucite®, Acrylite®, ModenGlass®, and Diakon®. The resin is polymerizedby the addition polymerization method and forms a plastic that isatactic and therefore amorphous.

The most important property of PMMA is its optical clarity. This plastichas a very high light transmittance. It is also quite insensitive to UVlight. It has low oxidation sensitivity, a high gloss, and overallweather resistance. Together, these characteristics result in a highretention of clarity and light transmittance over long periods of time.These desirable optical properties led to numerous and diverseapplications such as windshields (especially for aircraft), skylights,outdoor signs, boat surfaces, automobile tail lights, display cases,light fixtures, shower stalls, spas, bathroom basins, and counter tops,hot tubs, shelving and decorative laminates, among others.

The relatively low processing temperature, low shrinkage, and gooddimensional stability make PMMA easy to process in injection molding andextrusion. A major product for PMMA is acrylic sheet which can bethermoformed into many of the products mentioned earlier.

The popularity of acrylic sheets in these applications also means thatacrylic sheets are often exposed to high levels of moisture. In theareas of baths, showers, and spas the acrylic material is almostconstantly in contact with water. This is especially the case with spasand hot tubs which have considerable fluid volume and are therefore notdrained on a regular basis.

Water left in bath basins or spas for only a couple of days can becomefouled with numerous biological organisms. In many instances a yellow orbrownish scum line develops on the surface of the basin or spa near orat the interface of the standing water and air. With additional agingthe water becomes cloudy as algae, bacteria and fungi grow.

Even in areas where water does not stand for extended periods of time,e.g., bathroom sinks and basins, the frequency of wetting can lead tosubstantial bacterial and fungal growth.

In short, thermoformable acrylic sheeting is often used in applicationshaving high moisture exposure. Thus acrylic sheeting can serve as agrowth surface for bacteria, fungi and other microbes that areaesthetically unpleasing, damaging to the product (e.g., cause stainingor discoloration), and/or harmful to human health. Accordingly, there isa great need for a control strategy for successfully reducing orsubstantially eliminating the proliferation of microbes on acrylicsurfaces.

The majority of existing control strategies for reducing microbes onacrylic surfaces utilizes treatment of the water by application ofchemicals or topical application of antimicrobial agents. For example,in swimming pools and large hot tubs, the algae and the bacteria areusually controlled by the addition of an oxidant such as sodiumhypochlorite or an in situ generation of ozone, and by filtering thewater through diatomaceous earth. Such treatments are expensive and insmall applications, such as a bathroom basin, they are not an option.Bathroom basins and smaller hot tubs and spas typically require theapplication of topical antimicrobial solutions (e.g., bleach) followedby physical abrasion to remove built up bio-scum. Such topicaltreatments are time consuming and are not durable.

What is desired is a thermoformable acrylic sheet that has built-inantimicrobial protection that reduces or substantially eliminates theproliferation of bacteria, algae, fungi, and other microbes on itssurface. Such an acrylic sheet would also reduce and/or substantiallyeliminate the need for exterior treatment of the sheet or water.

Attempts at producing such sheeting are known from the prior art. Forexample, international publication WO 99/47595 discusses a biocidalplastic material comprising an acrylic polymer containing 5% to 50% of arubbery co-polymer and a biocidal compound. The polymer is purportedlysuitable for use in preparing extruded sheets for thermoformingapplications. Several biocides are discussed including triclosan,silver, isothiazolones, zinc pyrithione, 10-10′ oxybisphenoxyarsine(OBPA), and benzisothiazolin-3-one derivatives.

Similarly, European Patent Application EP 893,473 discusses athermoplastic acrylic sheet composition that can contain anantimicrobial composition. Trade names for OBPA and isothiazolones arementioned as possible antimicrobial agents. The '473 document, however,provides no guidance regarding effective amounts of antimicrobial agentsor how to incorporate them into the acrylic polymer.

Although some of the known acrylic sheets having built-in antimicrobialagents demonstrate some efficacy against the buildup of microorganisms,there is a continuing need for more efficacious antimicrobial sheeting.The reason for this continuing need is three-fold.

One reason is based in economics. The addition of some antimicrobialproducts into acrylic polymers increases the per-unit cost of sheetingto levels that are unacceptable to the consumer. The use of silver as anantimicrobial agent is a notable example.

Another reason is based in manufacturing problems. Most industrialacrylic sheet manufacturing processes are precisely controlled processesthat produce product with specific characteristics (e.g., opticalclarity). The addition of antimicrobial agents often alters the process(e.g., curing time) and/or results in unacceptable product (e.g., opaquesheeting). Inorganic antimicrobial agents such as silver and copper arenotable examples in that they tend to discolor thermoformed articles.

Finally, fungal growth remains a problem in spa and bath applications.

Accordingly, there is a need for a commercially acceptable solution tothe above discussed problems. This solution should provide an economicalalternative to existing antimicrobial acrylic products. This solutionshould also integrate into existing acrylic sheet manufacturingprocesses without causing unacceptable process changes. Finally, thesolution should demonstrate acceptable efficacy against fungal growth.

BRIEF SUMMARY OF THE INVENTION

The present invention derives from research directed at developing acommercially viable process for making a thermoformable acrylic sheetthat exhibits antimicrobial characteristics. One result of this researchis an antimicrobial additive composition that exhibits exceptionalefficacy against both bacteria and fungus when incorporated into acrylicpolymers. In one preferred embodiment, the additive compositionaccording to the invention comprises a quantity of an antimicrobialagent, namely alkyl dimethyl ammonium saccharinates; isothiazolines;oxathiazines; azoles; chlorothalonils; and mixtures thereof.

In a further embodiment the invention encompasses a polymer compositionhaving antimicrobial activity wherein the composition comprises anacrylic polymer and one or more of the above mentioned antimicrobialagents.

In yet another embodiment, the invention encompasses a method of makingan antimicrobial polymer composition. In this embodiment and quantity ofantimicrobial agent is added to an acrylic polymer material to form anantimicrobial acrylic polymer composition which may then be formed intosheets and other products. The antimicrobial agents used in thisembodiment are the same as those used in the other embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a picture of an acrylic disk after plating and incubation.

FIG. 2 is a picture of an acrylic disk that contains no antimicrobialagent after inoculation with a fungal species.

FIG. 3 is a picture taken along the edge of a disk made from thecomposition described in Table 1 of the Examples after inoculation witha fungal species.

FIG. 4 is a picture taken along the edge of a disk made from thecomposition described in Table 2 of the Examples after inoculation witha fungal species.

FIG. 5 is a picture taken along the edge of a disk made from thecomposition described in Table 3 of the Examples after inoculation witha fungal species.

FIG. 6 is a picture taken along the edge of a disk made from thecomposition described in Table 4 of the Examples after inoculation witha fungal species.

FIG. 7 is a picture taken along the edge of a disk made from thecomposition described in Table 5 of the Examples after inoculation witha fungal species.

FIG. 8 is a picture taken along the edge of a disk made from thecomposition described in Table 6 of the Examples after inoculation witha fungal species.

FIG. 9 is a picture of an acrylic disk after plating and incubation.

FIG. 10 is a picture of an acrylic disk that contains no antimicrobialagent after inoculation with a fungal species.

FIG. 11 is a picture taken along the edge of a disk made from thecomposition described in Table 7 of the Examples after inoculation witha fungal species.

FIG. 12 is a picture taken along the edge of a disk made from thecomposition described in Table 8 of the Examples after inoculation witha fungal species.

FIG. 13 is a picture taken along the edge of a disk made from thecomposition described in Table 9 of the Examples after inoculation witha fungal species.

FIG. 14 is a picture taken along the edge of a disk made from thecomposition described in Table 10 of the Examples after inoculation witha fungal species.

FIG. 15 is a picture taken along the edge of a disk made from thecomposition described in Table 11 of the Examples after inoculation witha fungal species.

FIG. 16 is a picture taken along the edge of a disk made from thecomposition described in Table 12 of the Examples after inoculation witha fungal species.

FIG. 17 is a picture taken along the edge of a disk made from thecomposition described in Table 13 of the Examples after inoculation witha fungal species.

DETAILED DESCRIPTION

As used herein, the term “antimicrobial” includes biostatic activity,i.e., where the proliferation of microbiological species is reduced oreliminated, and true biocidal activity where microbiological species arekilled. Furthermore, the terms “microbe” or “antimicrobial” should beinterpreted to specifically encompass bacteria and fungi as well asother single-celled organisms such as mold, mildew and algae.

As noted previously, the concept of making thermoformable acrylicsheeting having built-in antimicrobial agents is known as evidenced byWO 99/47595 and EP 893,473. Yet, to date, the known thermoformablesheets have not met with a high degree of commercial success for reasonsstated previously.

This commercial need led to the present invention, which is, in onebroad embodiment, a new combination of acrylic polymers and antifungalagents. The antimicrobial agents utilized in the practice of theinvention form an antimicrobial additive composition for impartingantimicrobial characteristics to acrylic polymers, thermoformableacrylic sheets, and articles made from such sheets. In particular, theseagents impart antibacterial and antifungal characteristics tothermoformable acrylic sheets at an acceptable cost and withoutdisrupting manufacturing processes and without unacceptably altering theend product.

The antimicrobial additive composition for imparting antimicrobialcharacteristics to thermoformable acrylic sheets according to theinvention comprises a quantity of an antimicrobial agent, namely alkyldimethyl ammonium saccharinates; isothiazolines; oxathiazines; azoles;chlorothalonils; and mixtures thereof. These agents are commerciallyavailable from a number of sources.

Particularly preferred isothiazolines include, but are not limited to,2-n-octyl-4-isothiazolin-3-one (CAS 26530-20-1) and N-butyl-1,2benzisothiazolin-3-one (CAS 004299-07-4). 2-n-octyl-4-isothiazolin-3-oneis commercially available from Rohm & Hass under the trade name SKANEM-8. N-butyl-1,2 benzisothiazolin-3-one is commonly known as Butyl-BIT(BBIT) and is commercially available from Avecia Chemical under thetradename VANQUISH 100.

A particularly preferred alkyl dimethyl ammonium saccharinate isavailable under the tradename ONYXIDE 3300 from Stepan Chemicals.ONYXIDE 3300 is described in registration materials as being an alkyl(50% C14, 40% C12, 10% C16) dimethylbenzyl ammonium saccharinate.

Chlorothalonil or 2,4,5,6-Tetrachloroisophthalonitrile (CAS No:1897-45-6) is commonly known as and sold commercially under the tradename BUSAN 1192 from Buckman Laboratories.

As used herein the term “azoles” should be interpreted to include any ofthe “azole” antimicrobial agents known to those skilled the art.Particularly preferred azoles include, but are not limited to,propiconazole and tebuconazole and mixtures of these two agents.Mixtures of these two agents have been shown to have a synergisticeffect that translates to improved efficacy at lower concentrations ofagents.

A particularly preferred oxathiazine is bethoxazin commerciallyavailable under the tradename BETHOGARD from Janssen Pharmaceutica.

For ease of discussion the above chemicals are collectively referred toherein as the “antimicrobial agents.”

One of the reasons that these antimicrobial agents are used in thepractice of the present invention is that they have shown acceptableefficacy at commercially acceptable concentrations. Furthermore, theyare soluble in PMMA and PMMA precursors and thus may be seamlesslyintegrated into existing processes or provided in the form of a premixedmasterbatch (i.e., they can be delivered via a polymeric carrier).

In a further embodiment the invention encompasses an acrylic polymercomposition having antimicrobial activity. The composition according tothe invention comprises an acrylic polymer material and one or more ofthe above mentioned antimicrobial agents.

The acrylic polymer composition comprises a homopolymer or copolymer ofat least one C₁₋₆ alkyl (C₀₋₈ alk)acrylate. Preferred acrylic materialsare homopolymers or copolymers of the methyl, ethyl, butyl,2-ethylhexyl, cyclohexyl or phenyl esters of acrylic acid or methacrylicacid.

The polymer chemistry underlying the base acrylic material utilized inthe practice of the invention is well known among those skilled in theart and will not be discussed in detail herein. As an aid to the reader,however, a brief synopsis of the two primary methods for forming acrylicsheet is provided.

In very general terms, the majority of acrylic sheeting is manufacturedin either a casting or an extrusion process. In a very basic extrusionprocess a quantity of PMMA pellets passed through a heated screwmelterwhere they are softened and then forced through a slot die into a sheetform. Usually the PMMA pellets are of a homopolymer or a copolymer thatis primarily PMMA but this percentage may vary depending upon theparticular process, designated end use, or the presence of otheradditives.

Extrusion processes typically run at fairly high temperatures, e.g.,around 200° C., and thus can vaporize or “boil off” organicantimicrobial agents such as those used in the practice of theinvention. For example, one popular organic antimicrobial agent istriclosan. Triclosan vaporizes at about 205° C. Accordingly, if organicantimicrobial agents are used in an extrusion process upward adjustmentsin antimicrobial agent loadings or other precautions such as addition atthe end of the extruder may be necessary to ensure sufficient retentionof antimicrobial agent in the final product.

The other primary sheet making process is a casting process. The castingprocess begins by making an acrylic “syrup” which in one basic form is asolution of PMMA polymer dissolved in MMA monomer that has beeninitiated with a peroxide or UV light. Acrylic syrup can also be made byinterrupting the polymerization process before the chains get very long.

After the syrup is made it is cast on a long, flat form to create asheet which is then allowed to cure. After the sheet has cured to theproper degree it can be manipulated and thermoformed in accordance withprocesses well known to those skilled in the art.

The invention may be utilized using either an extrusion or a castingprocess and may be utilized in either a continuous or batch process.Casting processes, however, are particularly well suited to the practiceof the invention. The invention is also suitable with curing conductedat room temperature or at an elevated temperature, and is thuscompatible with many different cure chemistries.

The composition of the acrylic material is selected according to theapplication in which the material is to be used. For example, if thematerial is intended to be cast in a sheet for subsequent thermoforming,e.g., to form a tub or spa; then an acrylic material formulated forcasting and thermal molding should be selected. Likewise, if thematerial is intended to be extruded those skilled in the art may alterthe composition for extrusion purposes without undue experimentation.

In preferred embodiments the combined weight concentration of theantimicrobial agent in the polymer composition (also known as the“active level”) is in a range from about 250 ppm to about 50,000 ppmbased upon the weight of the polymer. In particularly preferredembodiments the antimicrobial agent is present in the polymercomposition in a concentration range from about 500 ppm to about 10,000ppm. More particularly preferred embodiments utilize a range from about2000 ppm to about 6000 ppm.

If a combination of tebuconazole and propiconazole is used the broadestpreferred range for the tebuconazole and propiconazole ratio is betweenabout 90:10 and 10:90 tebuconazole to propiconazole. A more preferredrange is between about 60:40 and 40:60 tebuconazole to propiconazole.50:50 ratios are particularly preferred.

The polymeric material of the invention may have many applications. Itis useful as a resin for molding or extrusion applications, e.g., tomake doors or panels for interior or exterior cladding applications etc.It may be provided in the form of a sheet material, e.g., for providingwalls, linings, etc., or which may be suitable for forming into articlessuch as bathtubs, shower stalls, etc., by thermoforming. It may also beuseful in the form of a curable resin, e.g., a polymethyl methacrylateresin dissolved in methyl methacrylate and optionally containing adispersion of fillers, colors and other functional particles for themanufacture of sinks, worktops, countertops, etc.

A still further use of the polymer composition according to theinvention is as a coating over a base material. One benefit of this formof the invention is that a relatively small amount of the antimicrobialsactive polymer may be used to give antimicrobial function to the surfaceof a non-antimicrobial structure. The base material may be anotherpolymer, such as another acrylic layer, polyvinylchloride, or a styrenebased polymer for example.

The invention also embodies a method for manufacturing an antimicrobialacrylic polymer composition. The method comprises the steps of combininga quantity of antimicrobial agent with an acrylic polymer material toform an antimicrobial acrylic polymer composition wherein the combinedweight concentration of the antimicrobial agent in the polymercomposition is in a range from about 250 ppm to about 50,000 ppm basedupon the weight of the polymer composition. In particularly preferredembodiments the antimicrobial agent is added to the polymer compositionto provide a final concentration in a range from about 500 ppm to about10,000 ppm. More particularly, preferred embodiments utilize a rangefrom about 2000 ppm to about 6000 ppm.

If a combination of tebuconazole and propiconazole is used thepreferable ratio of tebuconazole to propiconazole is between about 90:10and 10:90, more preferably between about 60:40 and about 40:60, and mostpreferably around 50:50.

The antimicrobial agents can be combined with the acrylic polymer inseveral ways. For example, the antimicrobial agents may be combined withthe polymer post-polymerization in an extruder.

A more preferred method for combining the antimicrobial agent with theacrylic polymer is to mix the antimicrobial agent with one of theprecursors of the acrylic polymer. For example, the antimicrobial agentsmay be added to the MMA prior to combining the MMA with PMMA to make theacrylic syrup. Alternatively, the antimicrobial agents can be added tothe syrup before the syrup is cast. This addition can be directly to thesyrup prior to a mixing step or by adding via premixed sidestream as asolution in MMA with other ingredients.

In a still further embodiment the invention encompasses a method ofmanufacturing a thermoformable antimicrobial acrylic sheet. In broadterms the method comprises the steps of combining a quantity ofantimicrobial agent with an acrylic polymer material to form anantimicrobial acrylic polymer composition then forming the antimicrobialacrylic composition into a sheet.

The preferred weight concentrations and weight ratios of antimicrobialagents utilized in this embodiment of the invention are the same asthose utilized in previous embodiments and need not be repeated here.

In preferred embodiments the step of combining a quantity ofantimicrobial agent with an acrylic polymeric material to form anantimicrobial acrylic polymer composition comprises the step of mixingthe antimicrobial agent into a polymeric precursor of the acrylicpolymeric material. This precursor may be one of the individualcomponents that make up the acrylic such as methyl methacrylate (MMA) orthe acrylic polymer syrup that is made in casting applications. Theantimicrobial agents can also be added post-polymerization in anextruder.

After the antimicrobial agent is added to the polymer material themethod further comprises forming the resulting polymer composition intoa thermoformable acrylic sheet. The preferred methods of forming thesheet are casting or extrusion as known by those skilled in the art anddiscussed above.

After the sheet is formed it may then be thermoformed or otherwisemodified using known methods to create any number of products includingbut not limited to windshields (especially for aircraft), skylights,outdoor signs, boat surfaces, automobile tail lights, display cases,light fixtures, shower stalls, spas, bathroom basins, and counter tops,hot tubs, shelving and decorative laminates.

EXAMPLES

The following examples are provided as an aid to the reader and shouldnot be interpreted as limiting the scope of the invention in any way.Those skilled in the art are well aware that there are numerousmodifications that can be made in the manufacture of acrylic polymer(e.g., casting formulations vs. extrusion formulations). The claimedinvention is capable of adaptation to these various alternatives withoutundue experimentation.

Example 1

A 50 gram sample of acrylic syrup of approximately 10% PMMA and 89.5%MMA and 0.5% antimicrobial agent was prepared. The antimicrobial agentwas bethoxazin commercially available as BETHOGARD from JanssenPharmaceutica. The syrup consisted of

about 43.9 grams of MMA

about 0.25 grams of BETHOGARD

about 4.91 grams of PMMA

about 0.1 grams of CaOH

about 0.1 grams (0.1 ml) H₂O

about 0.25 grams (0.3 ml) L. mercaptan

about 0.5 grams ESPEROX 41-25 (Tert-butyl monoperoxymaleate)

This material was then cast into small circular silicone molds andallowed to cure. Curing was conducted at room temperature. After 24hours translucent acrylic disks were removed from the molds andevaluated for efficacy.

Each disk demonstrated acceptable efficacy at or below approximately5000 ppm antimicrobial agent based upon the weight of the polymer.

Example 2

Approximately 50 gram samples of each of the following antimicrobialacrylic compositions were prepared to be cast into disks:

(a) Antimicrobial Syrup at 5000 ppm (0.5% Final Level in Formulation) ofButyl-BIT

This composition contained approximately 5000 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas Butyl-BIT (i.e.,VANQUISH 100) which is approximately 100% activeingredient. The components of the composition are set forth in Table 1.

TABLE 1 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 97.6 48.8 g approx. 75% MMA with inhibitors) VANQUISH100 0.5 0.25 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml) Lauryl Mercaptan0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(b) Antimicrobial Syrup at 7500 ppm (0.75% Final Level in Formulation)of Butyl-BIT

This composition contained approximately 7500 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas Butyl-BIT (i.e., VANQUISH 100) which is approximately 100% activeingredient.

TABLE 2 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 97.1 48.55 approx. 75% MMA with inhibitors) VANQUISH100 1.0 0.375 CaOH 0.2 0.1 H₂O 0.2 0.1 g (0.1 ml) Lauryl Mercaptan 0.50.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(c) Antimicrobial Syrup at 5000 ppm of 2-n-octyl-4-isothiazolin-3-one

This composition contained approximately 5000 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas 2-n-octyl-4-isothiazolin-3-one (i.e. SKANE-M8) which isapproximately 45% active ingredient.

TABLE 3 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 96.99 48.495 g approx. 75% MMA with inhibitors)SKANE-M8 1.11 0.555 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml) LaurylMercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(d) Antimicrobial Syrup at 7500 ppm of 2-n-octyl-4-isothiazolin-3-one

This composition contained approximately 7500 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas 2-n-octyl-4-isothiazolin-3-one (i.e. SKANE M-8) which isapproximately 45% active ingredient.

TABLE 4 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 96.43 48.215 approx. 75% MMA with inhibitors)SKANE-M8 1.67 1.11 CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml) LaurylMercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(e) Antimicrobial Syrup at 5000 ppm of Bethoxazin.

This composition contained approximately 5000 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas Bethoxazin (i.e. BETHOGARD) which is approximately 100% activeingredient.

TABLE 5 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 97.6 48.8 g approx. 75% MMA with inhibitors)BETHOGARD 0.5 0.25 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml) LaurylMercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(f) Antimicrobial Syrup at 7500 ppm of Bethoxazin

This composition contained approximately 7500 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas Bethoxazin (i.e. BETHOGARD) which is approximately 100% activeingredient.

TABLE 6 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 97.1 48.55 approx. 75% MMA with inhibitors) BETHOGARD1.0 0.375 CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml) Lauryl Mercaptan 0.50.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

Each of the above acrylic compositions were prepared and cast into disksby the following method. The amount of acrylic syrup was weighed into adisposable plastic beaker. Liquid additives were weighed directly in thebeaker. The solution was stirred completely. Calcium hydroxide powderwas added by weighing it out onto weigh paper, then pouring intosolution, and stirring completely. The solution was stirred using amagnetic stir bar. Water and Lauryl Mercaptan were added nextvolumetrically using a graduated pipette. The solution was stirredcompletely. Esperox 41-25 was added directly to the beaker and stirredin completely. A small reaction occurred forming bubbles and causing aslight color change to a very light orange. The solution was poured intosilicone molds within two minutes of adding Esperox 41-25 and allowed tocure. Curing was conducted at room temperature. The compositions wereeach tested in accordance with AATCC Test Method 30 Part III. The testorganism was Aspergillus niger 6275.

As specified by the test method, the disks were plated in the middle ofa nutrient agar lawn seeded with Aspergillus niger. In addition,nutrient agar containing the specified concentration of Aspergillusniger was poured on the surface of the test samples.

Fresh acrylic surfaces are typically extremely smooth. Therefore, thesample surfaces were crosshatched with a razor blade to roughen thesurface and improve inoculum retention. Roughening the surface improvesthe “bite” and assists the fungal organisms in anchoring and rooting tothe surface.

The test samples were then incubated for a period of 7 days in acontrolled chamber with high humidity. Exemplary test results areprovided in the figures.

FIG. 1 shows an example of a plated acrylic sample after a period ofIncubation.

FIG. 2 is a picture taken along the edge of a section of a control diskwhich contained no antimicrobial agent. Significant fungal overlap waspresent along the edges of the disk. (Note the dark dots within thelight colored region.)

FIG. 3 is a picture taken along the edge of a disk made from thecomposition described in Table 1. The edges of the disk were free offungal overlap.

FIG. 4 is a picture taken along the edge of a disk made from thecomposition described in Table 2. The edges of the disk were free offungal overlap.

FIG. 5 is a picture taken along the edge of a disk made from thecomposition described in Table 3. There was good antifungal efficacy.

FIG. 6 is a picture taken along the edge of a disk made from thecomposition described in Table 4. Excellent antifungal efficacy wasdemonstrated and there was a zone of exclusion of 7 mm to 9 mm aroundthe disk.

FIG. 7 is a picture taken along the edge of a disk made from thecomposition described in Table 5. The edges of the disk showedsignificant fungal overlap.

FIG. 8 is a picture taken along the edge of a disk made from thecomposition described in Table 6. The edge of the disk showed signs ofimpending fungal overlap.

Example 3

Approximately 50 gram samples of each of the following antimicrobialacrylic compositions were prepared to be cast into disks:

(a) Antimicrobial Syrup at 10,000 ppm (1% Final Level in Formulation) of2-n-octyl-4-isothiazolin-3-one

This composition contained approximately 10,000 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas 2-n-octyl-4-isothiazolin-3-one (i.e. SKANE M-8) which isapproximately 45% active ingredient.

TABLE 7 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 95.88 47.94 g approx. 75% MMA with inhibitors) SKANEM-8 2.22 1.11 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml) Lauryl Mercaptan0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(b) Antimicrobial Syrup at 10,000 ppm of Triclosan.

This composition contained approximately 10,000 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas triclosan (i.e. IRGASAN DP 300) which is approximately 100% activeingredient.

TABLE 8 % of Weight in Grams or Component Composition Milliliters Syrup(approx. 25% PMMA; 97.1 48.55 g approx. 75% MMA with inhibitors) IRGASANDP 300 1.0 0.5 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml) Lauryl Mercaptan0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(c) Antimicrobial Syrup at 10,000 ppm of Mixture of Propiconazole andTebuconazole

This composition contained approximately 10,000 ppm of a mixture ofactive antimicrobial agents. The antimicrobial agents used in thiscomposition were in a 1:1 ratio and were propiconazole (i.e. WOCOSENTECHNICAL) and tebuconazole (i.e. PREVENTOL A8), which are eachapproximately 100% active ingredient.

TABLE 9 Syrup (approx. 25% PMMA; 97.1 48.55 g approx. 75% MMA withinhibitors) WOCOSEN/PREVENTOL A8 1.0 0.5 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g(0.1 ml) Lauryl Mercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(d) Antimicrobial Syrup at 10,000 ppm of Butyl-BIT

This composition contained approximately 10,000 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas Butyl-BIT (i.e. VANQUISH 100) which is approximately 100% activeingredient.

TABLE 10 Syrup (approx. 25% PMMA; 97.1 48.55 g approx. 75% MMA withinhibitors) VANQUISH 100 1.0 0.5 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml)Lauryl Mercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(e) Antimicrobial Syrup at 10,000 ppm of Bethoxazin

This composition contained approximately 10,000 ppm of activeantimicrobial agent. The antimicrobial agent used in this compositionwas Bethoxazin (i.e. BETHOGARD) which is approximately 100% activeingredient.

TABLE 11 Syrup (approx. 25% PMMA; 97.1 48.55 g approx. 75% MMA withinhibitors) BETHOGARD 1.0 0.5 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml)Lauryl Mercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(f) Antimicrobial Syrup at 10,000 ppm of Alkyl Dimethylbenzyl AmmoniumSaccharinate

This composition contained approximately 10,000 ppm of activeantimicrobial agent. The antimicrobial used in this composition wasalkyl dimethylbenzyl ammonium saccharinate (i.e. ONYXIDE 3300) which isapproximately 100% active ingredient.

TABLE 12 Syrup (approx. 25% PMMA; 97.1 48.55 g approx. 75% MMA withinhibitors) ONYXIDE 3300 1.0 0.5 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml)Lauryl Mercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

(g) Antimicrobial Syrup at 10,000 ppm of Chlorothalonil

This composition contained approximately 10,000 ppm of activeantimicrobial agent. The antimicrobial used in this composition waschlorothalonil (i.e. BUSAN 1192) which is approximately 100% activeingredient.

TABLE 13 Syrup (approx. 25% PMMA; 97.1 48.55 g approx. 75% MMA withinhibitors) BUSAN 1192 1.0 0.5 g CaOH 0.2 0.1 g H₂O 0.2 0.1 g (0.1 ml)Lauryl Mercaptan 0.5 0.25 g (0.3 ml) Esperox 41-25 1.0 0.5 g

Each of the above acrylic compositions were prepared and cast into disksby the following method. The amount of acrylic syrup was weighed into adisposable plastic beaker. Liquid additives were weighed directly in thebeaker. The solution was stirred completely. Calcium hydroxide powderwas added by weighing it out onto weigh paper, then pouring intosolution, and stirring completely. The solution was stirred using amagnetic stir bar. Water and Lauryl Mercaptan were added nextvolumetrically using a graduated pipette. The solution was stirredcompletely. Esperox 41-25 was added directly to the beaker and stirredin completely. A small reaction occurred forming bubbles and causing aslight color change to a very light orange. The solution was poured intosilicone molds within two minutes of adding Esperox 41-25 and allowed tocure. Curing was conducted at room temperature. The compositions wereeach tested in accordance with AATCC Test Method 30 Part III. The testorganism was Aspergillus niger 6275.

As specified by the test method, the disks were plated in the middle ofa nutrient agar lawn seeded with Aspergillus niger. In addition,nutrient agar containing the specified concentration of Aspergillusniger was poured on the surface of the test samples.

Fresh acrylic surfaces are typically extremely smooth. Therefore, thesample surfaces were crosshatched with a razor blade to roughen thesurface and improve inoculum retention. Roughening the surface improvesthe “bite” and assists the fungal organisms in anchoring and rooting tothe surface.

The test samples were then incubated for a period of 7 days in acontrolled chamber with high humidity. Exemplary test results areprovided in the figures.

FIG. 9 shows an example of a plated acrylic sample after a period ofincubation.

FIG. 10 is a picture taken along the edge of a section of a control diskwhich contained no antimicrobial agent. Significant fungal overlap ispresent along the edges of the disk.

FIG. 11 is a picture taken along the edge of a disk made from thecomposition described in Table 7. The edges of the disk showed excellentresistance to fungal coverage. The sample surface was extremely clean.

FIG. 12 is a picture taken along the edge of a disk made from thecomposition described in Table 8. Resistance against fungal growth wasminimal. There were microscopic signs of fungal overlap over the edge ofthe disk.

FIG. 13 is a picture taken along the edge of a disk made from thecomposition described in Table 9. The disk was clean but there were thebeginnings of fungal overlap onto the surface of the disk.

FIG. 14 is a picture taken along the edge of a disk made from thecomposition described in Table 10. Excellent antifungal efficacy wasdemonstrated. There were microscopic signs of fungal overlap over theedge of the disk.

FIG. 15 is a picture taken along the edge of a disk made from thecomposition described in Table 11. The disk showed very clean edges andsurfaces.

FIG. 16 is a picture taken along the edge of a disk made from thecomposition described in Table 12. Resistance against fungal growth wasminimal.

FIG. 17 is a picture taken along the edge of a disk made from thecomposition described in Table 13. Resistance against fungal growth wasminimal.

It will therefore be readily understood by those persons skilled in theart that the present invention is susceptible of broad utility andapplication. Many embodiments and adaptations of the present inventionother than those herein described, as well as many variations,modifications and equivalent arrangements, will be apparent from orreasonably suggested by the present invention and the foregoingdescription thereof, without departing from the substance or scope ofthe present invention. Accordingly, while the present invention has beendescribed herein in detail in relation to its preferred embodiment, itis to be understood that this disclosure is only illustrative andexemplary of the present invention and is made merely for purposes ofproviding a full and enabling disclosure of the invention. The foregoingdisclosure is not intended or to be construed to limit the presentinvention or otherwise to exclude any such other embodiments,adaptations, variations, modifications and equivalent arrangements.

1. A method of manufacturing an antifungal acrylic polymer compositioncomprising: combining a quantity of an antifungal agent and an acrylicprecursor solution; and polymerizing the precursor solution to form anacrylic polymer composition; wherein the weight concentration ofantifungal agent in the polymer composition is in a range from about 250ppm to about 50,000 ppm based upon the weight of the polymercomposition; and wherein the antifungal agent is selected from the groupconsisting of isothiazoline, an oxathiazine, an azole, and a mixturethereof.
 2. The method according to claim 1, wherein the antifungalagent is an isothiazoline selected from the group consisting of2-n-octyl-4-isothiazolin-3-one and N-butyl-1,2 benzisothiazolin-3-one.3. The method according to claim 1, wherein the oxathiazine isbethoxazin.
 4. The method according to claim 1, wherein the antifungalagent is an azole selected from the group consisting of propiconazole,tebuconazole, and a mixture thereof.
 5. The method according to claim 1,further comprising forming the antifungal acrylic polymer compositioninto a thermoformable sheet.
 6. The method according to claim 1, whereinthe antifungal agent is present in an amount from about 500 ppm to about10,000 ppm.
 7. The method according to claim 5, further comprisingmolding the thermoformable acrylic sheet into a product.
 8. The methodaccording to claim 7, wherein the product is selected from the groupconsisting of windshields, skylights, outdoor signs, boat surfaces,automobile tail lights, display cases, light fixtures, shower stalls,spas, bathroom basins, and counter tops, hot tubs, shelving, decorativelaminates and other structural items.